Problems Attaching SCSI-2 Devices to SCSI-3 Adapter

 Last reviewed: September 25, 1997
Article ID: Q168094
The information in this article applies to:
  • Microsoft Windows NT Workstation versions 3.51 and 4.0
  • Microsoft Windows NT Server versions 3.51 and 4.0

SYMPTOMS

After you attach a 50-pin or Centronics SCSI-2 hard disk, scanner, tape Drive, or other device to a 68-pin SCSI-3 interface, your computer may stop responding or not respond when accessing SCSI bus. You may or may not see any events in the event log indicating a problem.

RESOLUTION

Obtain a proper SCSI-2 to SCSI-3 conversion cable or terminator.

STATUS

The third-party contact information included in this article is provided to help you find the technical support you need. This contact information is subject to change without notice. Microsoft in no way guarantees the accuracy of this third-party contact information.

For additional information, please see the following article in the Microsoft Knowledge Base: 

   ARTICLE-ID: Q101352
   TITLE     : Properly Connecting SCSI Devices to Windows NT

MORE INFORMATION

A SCSI-2 device uses a low control byte, but SCSI-3 devices have both a high and a low control byte. When going from a SCSI-3 interface down to a SCSI- 2 device, the SCSI-3 high byte needs to be terminated while letting the low byte pass through (see Diagram 1). Most SCSI-3 to SCSI-2 cables do not have proper termination and need a special adapter for the high byte to terminate. Unless the documentation that comes with the conversion cable states that it terminates the high byte, proper termination will not happen and possible data corruption can occur.

Diagram 1 

           SCSI-3 (68-Pin)                               SCSI-2 (50-Pin)

             High Byte            |------------------|
          ------------------------| Terminated       |
                                  |                  |
             Low Byte             |                  |    Low Byte
          -----------------------------------------------------------------
                                  |------------------|
For additional information, please see the following article in the Microsoft Knowledge Base: 

   ARTICLE-ID: Q154690
   TITLE     : How to Troubleshoot Event 9 and 11 Error Messages
You may also visit Adaptec's Web site: 

   http://www.adaptec.com/support/connect/index.html
See Connecting 8-Bit and 16-Bit Devices to an Adaptec Wide Host Adapter.

Additional query words: prodnt tape drive ultra wide fast
Keywords : ntsetup NTSrvWkst kbhw kbsetup kbtshoot
Version : WinNT:3.51,4.0
Platform : winnt

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Last reviewed: September 25, 1997
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